Fig. 3. CRM1-independent nucleocytoplasmic shuttling of STAT2-EGFP. (A) NIH3T3 cells stably expressing STAT2-EGFP (left) or STAT1-EGFP (right) were treated for 4 hours with LMB (10 ng/ml) and subsequently subjected to cytoplasmic FLIP analysis. A cytoplasmic area was bleached with maximum laser intensity by scanning up to nine consecutive periods of 35-43 seconds. The bleached regions are indicated with white rectangles in the first post-bleach images. The total fluorescence of the bleached cells and that of the neighboring cells was monitored between bleaching. The representative image series shows the fluorescence intensities in false color codes (intensity increases from blue to red) before (0 sec) and after the indicated bleaching periods. (B) The nuclear fluorescence intensities of the bleached cells were measured in different experiments, normalized to the total fluorescence of the respective unbleached cells and plotted over time. The relative fluorescence intensities of STAT2-EGFP (left) and STAT1-EGFP (right) in the nucleus are shown during a period of 300 seconds. Colors of graphs reflect individual experiments.